1 . making
reconstruction of precooling system of oxygen making machine ., 制氧机预冷系统改造.
2 . made
He bought some home - made explosives from the street traders ., 他从小商贩那儿买了一些土制炸药.
3 . preparation
preparation of powdered - tellurium by reduction from sulfuric acid solution ., 从硫酸溶液中还原制取金属碲粉.
4 . production
production of ferric oxide from waste lron mud ., 用铁泥制氧化铁红.